Abstarct: The uniformity or consistency in verb tenses is at the heart of maintaining the sense of coherence in academic writing, and so the Iraqi EFL students have a hard time dealing with tense variation in the text, especially in the narrative ones. These mistakes are usually caused by structural variations between the Arabic and English language and lack of exposure to the real-life English other than in classrooms, which compromises the clarity and accuracy of the writing of students. The aim of the study will be to examine the most frequent verb tense shift and the errors in the narrative writing of EFL learners, Iraqi undergraduate learners, and to explore how the pattern of Arabic tense and aspect affects the development of interlanguage learners. In particular, the experiment aims at categorizing the types of tense shift errors and discussing the linguistic and cognitive determinants that lead to their maintenance. An experimental design of mixed-method was utilized as controlled. A sample of 30 Iraqi undergraduates with intermediate level proficiency was requested to write narrative texts under standard conditions. Their writings were examined in terms of frequency and kinds of tense shift-violation, whilst semi-structured interviews were conducted to reveal awareness of learners of tense rules and the writing patterns. The results showed that the most common mistake was unnecessary switching between past and present tenses, which was mostly due to the Arabic structure and the lack of full knowledge of the English rules. The results of these studies indicate the significance of the application of certain pedagogical intervention methods focused on the consistency of tenses in long texts. The study is a contribution both to the theoretical model of interlanguage and the practical improvement of the EFL teaching.